题解 | #字母大小写转换#

import java.util.Scanner;
public class Main {
    
    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()) {
            String str = sc.next();
            char c = str.charAt(0);
            int cint = (int)c;
            if(cint >= 65 && cint <= 90) {    // 大写字母
                System.out.println((char)(cint+32));
            } else if (cint >= 97 && cint <=122) {    // 小写字母
                System.out.println((char)(cint-32));
            }
        }
    }
}